What these data indicate? In my view the authors made one correct and one wrong interpretation. First, they were correct to conclude that T cell response to IBD could be directed to "old" microbiota antigens rather than "new" never before seen microbiota-derived antigens. So basically in IBD we are losing tolerance rather than gaining immunity to microbiota antigens.

However, they made wrong conclusion that naïve T cells are converted into Tregs in vivo based on context (normal versus IBD). In their study loss of Treg generation is inhibited either during IBD-conditioning or in RAG KO hosts which could argue alternatively that such outcome has to do with failure of naïve T cells to interact with existing Tregs specific for the same or similar antigens in these scenarios (IBD or RAG-KO).